Ashford Designer Outlet – Membrane Replacement and Reconfiguration of the UK's Largest Tensile Fabric Roof

Description

The kilometre-long tensile fabric roof at the McArthurGlen Designer Outlet in Ashford, Kent, designed by Richard Rogers Partnership, has been a landmark in the Kent landscape for two decades (see the separate TensiNet entry for the original build). Architen Landrell, which installed the original roof, returned in 2014 to replace the membrane, and again when the owner expanded the centre to create a more modern shopping environment while keeping the roof as its centrepiece.

Chapman Taylor's expansion design, with Applied Landscape Design, removed the food-court section of the original teardrop-shaped canopy and added two curved lines of canopy on either side to form a new southern entrance. Modifying a working tensile structure on this scale had not been attempted before. Because every panel depends on its neighbours for tension and stability, the design team built a 3D model of the whole canopy and simulated how the new geometry would affect the existing membrane, to establish which panels had to be replaced and which parts of the steelwork had to change.

Removing the food court meant taking out four 25m-high masts. Instead of a roof braced through 360 degrees, the new form concentrates load at its new ends, where the tension taken to ground is comparable to the weight of a fully loaded Boeing 747. The new masts were so long they needed an escort vehicle, and the foundations measure about 15m x 15m, roughly three storeys deep. The structure was stabilised with temporary works, then over 182 days on site the panels were removed and replaced incrementally, with the remaining membrane monitored throughout.

The works also added 11 tensioned sails leading pedestrians from the railway station and a new fabric play canopy at the heart of the site. The scheme was Highly Commended for Shopping Centre and Outlet Centre Renovation at the 2020 Global RLI Awards.

Client/building owner: The Ashford Investor (McArthurGlen Designer Outlet). Architect: Chapman Taylor, with Applied Landscape Design. Engineers: Buro Happold; Tensys. Membrane: Mehler Texnologies (Valmex Mehatop F1 FR 1000). Membrane design, fabrication and installation: Architen Landrell.

Description of the environmental conditions